Power installation



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y, PactentedJa'n. 9, 1945 Stanley Smith Cook.' and L Wallsend-on-"Iyne, England,A Parsons Marine Steam Turbine() ous Mortimer Douglas, assgnors to The ompany Lim- 'ted, Wallsend-on-Tyne, England applicationl In Great Britain November*` 18,

6 claims. (clito-97e) mediate vstage of its expansion. Y

When such installations operate with av varying load, in certain conditions of working it is necessary to protectvthe' reheater and any steam passingl therethrough from attaining vtoo high a For'instance, in normal' full [power aheadjop'eration steam from thefsuperheater passes through a pressure and temperature are reduced before it passesv through the/reheater, butfwhen'going astern. the steam is not returned from the turbine system to the reheater so that unless other provision is made there is `under these conditions nov flow through thereheater which would consequently .be liable to attain an excessive'temper`l Proposalsv Y ditions, for example, iIi British Patent No. 416,091, in which ysteamdirected from thel superheater to thefasternturbine is first. passed through a reducing valve and superheater wherein its' pressure and vtemperature arereduced `and then` passed through the reheater on its way to the astern. turbine.

l 'IheA main object 'of the present invention is to provide asimplied means Aof overcoming the abovef condition, i. e.,r of protecting the reheater from overheating, under conditions ,in which such overheating is liable to occur.

Thezpresent invention consists briefly in an elastic fluid; powerf installation of the kind indicated` above wherein steam from the superheater directed to the. astern turbine is ycaused topass turbine or turbines wherein its v pressure turbine a, an

on. its,r way thereto inv superheatedcondition t through the reheater and the heating applied to the-reheater is reduced. y

Referring to the==accompanying drawings- Figure 1 shows'one convenientarrangement embodying the present invention;`

diagrammatic FgurefZisfa frontview partly in cross section.

of;Ev a *convenienti arrangementA ofthe'. control Figure 3 isa seotional vplanl of' Figure 2` on" the linelII-III thereof' c Fi'gurefi is a side' view'partly in sectionl 'of part offFgureli; c' Figure 5^'V is'a sectional plan view of part of Aa ino'ded valve arrangement; f

Figurel 6 is a vertical sectional viewtakeirnalf on the: onejline and half on another linethrough Fiauei Figure? isy asectionalviewof part of thecastingshown in Figures Sand 6;v c

Figure 8 'is a diagrammatic vview 'of a boiler having a superheater and reheater each provided withmanual means for varying the'rate of ilow of flue gases therethrough.r

lFigure 9` illustrates` part' of an arrangement embodying a servo-motor to control a damper or dampers operated in accordance with the poe sition'of two astern control valves. t

Figure `10 illustrates means damper position in accordance with the temperature of reheater outlet steam, and r Figures 11` and 12 show a system of linkages which may conveniently be'employed in conjunction` with the apparatus shown in Figure 10.

' vInfcarrying the invention into effect -in one'f'orm illustrated rby way ofl example in Figure 1 as applied to a marine installation employing a highintermediate-pressure turbine b, a low-pressureturbine c and an astern turbine d, we provide-a boiler e' with superheater the upper valve is contained in the upper compartment, the valves in each pair being mounted on a ,common operating spindle so as to be simultaneously operable. A steam connection 9' is provided from the lower compartment-under control of vthe lower ahead valve V1-to the high pressure turbine a whence a further connection for regulating the lc leads by 'way of a non-return valve m to a steam union n communicating with the reheater g. The remaining connection o to the steam union f1: is taken from the lower compartment z' underthe control of the lower astern'valve V3;

A connection@ is 'rnade'from` the outlet of the reheater g to the uppervalve chest compartment h' from which two further controlled steam connections qr are made', one (r) being underv control of the upper ahead: valve' V2 to the intermediatepressure turbine b and the other (q) being under control of the upper astern valveVt' to the astern vturbine d.

The outlet of the astern turbine isf/connected directly or through a low pressure astern turbine to a condenser (not shown) and the outlet s of the intermediate pressure turbine b is connected to the low-pressure turbine c, the outlet from which is also connected to the condenser.

The reheater g is provided with damping means (not shown) whereby the heating of the reheater tubes can be reduced as desired, this operation being performed either automatically in conjunction with the opening of the astern valves V3, V4 or in accordance with the temperature of the steam entering or leaving the reheater or manually. Y

In operation, when the ahead Valves V1, V2

are open and the astern valves V3, V4 closed,y

steam passes from the superheater f to the highpressure turbine a, thence through the non-return valve m, reheater g, intermediate-pressure turbine b and low-pressure turbine c. When the astern valvesI V3, V4 are open and the ahead valves V1, V2 are closed, steam from the superheater f passes through the reheater g, which is now damped, either automatically or manually, and thence passes to the astern turbine d; steam is prevented by the non-return valve m from passing backwards from the reheater g through the high-pressure turbine a.

If desired, when running astern the superheater f may also be furnished with damping means so that the heating of the superheater may also be reduced under these conditions.

In practice it is preferred that each pair of astern and ahead control valves be mounted on separate spindles and simultaneous operation of the valves of each pair ensured by the provision of suitable means.

According to one example as illustrated in Figures 2 to 4, such means consist of a rigid crossbar 2 connecting each pair of valve spindles 3, 4 where they project through glands 5, G in the valve chest casing.

As regards each pair of valves' a single operating hand wheel i is provided on a screwed shaft I l bearing against a further crossbar 9 loosely carried upon the valve spindles 3, 4. Compression springs i9, Il and link bolts l2 are provided between the two crossbars 2, 9 and the arrangement is such that starting from the full open position of the valves as the hand wheel is turned to close the valves the crossbar 9 moves and transmits closing force to the crossbar 2 by Way of the compression springs l0.

When the valves reach their seatings `further movement of the crossbar 9 further compresses the springs l and Il and tightly closes the valves upon their seatings; finally, a cap I3 on the hand wheel screw i4 bears against an abutment l5 at the centre of the crossbar 2. When opening movement is given to the hand wheel 1, the crcssbar 9 moves away from the crossbar 2 and the compression springs l0, Il extend until the link bolts l2 become operative and the valves are drawn away from their seatings.

Each pair of valves, that is to say, both ahead and astern valves, have a similar operating gear with a single hand wheel.

According to an alternative constructional arrangement illustrated in Figures 5 to 7, the astern valves V3, V4 incorporate a further shutoff and a leak-01T piston valve t operating to control a leak-o1f port u and a port t communicating with the outlet -wleading to the astern turbine b. The operation of the leak-01T valve t is similar to that of the valve t of British Patent No. 319,818.

An example of the manner in which the reduction of reheater temperature may be performed manually is illustrated in Figure 8, which shows a boiler of the type described in the British patent specication No. 539,614. In this iigureg is the reheater and j the superheater, each provided with a damper D for varying the rate of ow of flue gases therethrough. The dampers are each. provided with a hand lever L by which they are manually operated, the full and dotted lines indicating the fully closed and the fully open positions respectively.

Figure 9 illustrates means for controlling the operation of a servo-motor S in accordance with the position of the astern control valves V3 and V4, the servo-motor S providing means for openingk and closing the damper or dampers. The piston P of a pilot Valve is connectedby rocking lever A with xed pivot B, to valve Vs so that its position is determined by the latter.

Fluid under pressure is supplied to the pilot valve at F and is drained therefrom at1C. In the position shown with valves V3, V4, closed the pilot valve is so disposed that pressure iuid passes through port E to the space G on one side of the piston I-I of the servo-motor while the space J on the other Side is connected by port K to drain C. rPhe pressure fluid acting on the piston H presses it into the position shown which ;`1 corresponds to the fully open position of the lampers. When the valves V3, V4, are opened the pilot valve piston P is moved into the position whereby pressure fluid passes by port K to the space J whilst space G is connected by port E and duct M to drain C so that the piston H is moved to the opposite end of the servo-motor vcylinder to close the dampers.

In Figure 9 the width of the piston portions of pilot Valve P is substantially the same as the width of the ports E and K and the laps are very small so that a small opening movement of the valve V3 effects the change-over of the pressure fluid connections to operate the servo-motor and close the damper. The mechanism for op erating the pilot Valve piston P and opening Valve YV3 may have a lost-motion device so arranged that the valve P is operated and the damper closed beforefVs is actually open. Alternatively the pilot valve may be operated by the ahead valves V1 and V2 so that` the damper is closed as soon as the ahead valves are closed. In this case preferably both the superheater and reheater dampers are closed when the ahead valves are closed.

Figure 10 illustrates means 'for regulating the position of the damper in accordance `with the temperature of the steam leaving the heater. The steam from the heater passes through pipe N to which the` pilot valve casing Q is rigidly attached at T. The pilot valve piston P is connected by rocking lever V with xed pivot W, to rod X which is rigidly attached to the pipe N at U so that relative expansion of pipe N between the points T and U will cause the piston P to move to the right relatively to its casing Q. Pressure fluid is supplied to the latter `at F and is drained therefrom at C. vThe ports El and K of the pilot valve are formed in a sleeve Y which is connected by rocking lever 23 with xed pivot 24, to rod 25 carrying the piston H of the servo- `motor operating the damper D. The motion of At all temperatures below the normal the pilot valve P is to the left of its null position and pressure iiuid passes'through port E' to space G while space J is connected by port K to the drain C so that the pistoni-I is to the extreme right and the` damper fully open. When i the temperature reaches the normal the piston P reaches the null position and any further increase in temperature causes it to move to the right so that pressure iiuid passes by port K to space J and iiuid in space G passes to the drain C through p ort E and ducts M. The piston H is therefore moved to the left closing the damper and the motion communicated through lever 23 to the sleeve Y moves the latter to the right. When the sleeve Y reaches the null position in relation to piston P the flow of pressure iiuid to and from the servo-motor ceases and the closing motion of the at normal temperature.

As shown the movement communicated 'to the pilot valve P is by a simple lever V and the follow up motion of sleeve Yis by a simple lever 23 but in order to obtain reasonably large motion of piston H with the small movement practically obtainable by diierential thermal expansion of pipe N and rod X, etc., either the movement'oi P must be much more amplied or the motion of Y much more reduced than is practicable withA a single lever. Figures 11 and 12 show a system of linkage for effecting a considerable reduction of the motion of Y relatively to lI-I, this being the preferred method. The long arm 30 of the bell crank lever on a fixed pivot 3| is connected to the piston rod 25 of the servo-motor while the y short arm 32 is connected by link 32 to the long high `pressure turbine to arm 33 of another bell crank lever with a fixed fpivot 34, the short arm 35 being connected to the stem 3B of the sleeve Y. Figure 11 shows this linkage with the damper fully open and Figure l2 with the damper fully closed. y

In installations in accordance with this invention the passing of the steam from the superheater in its superheated condition through the rreheater together with the reduction of the heating applied to the reheater provides asimple and effective means of preventing the reheater `or the steam passing therethrough from attaim ing an excessive temperature.

What is claimed is:

1. An elastic fluid marine turbine power in stallation embodying an ahead turbine, an astern turbine, a superheater for initially heating the elastic fluid for the ahead turbine, a reheater for reheating exhaust steam at some intermediate stage of its expansion, in combination ywith means for directing elastic uidfrom the superheater in superheated condition through the reheater'to the astern turbine and means for reducing the heating applied to the reheater.

2. An elastic fluid power installation as claimed in claim 1, in combination with means operating automatically in conjunction with the opening of the astern valves ior reducing the heating of the reheater.

3. An elastic fluid` power installation as claimed in claim 1, in which means are provided for damping of the superheater.

4. An elastic fluid power installation as claimed in claim 1, having in combination a pair of simultaneously operable valves for ahead running, one controlling supply of` superheated steam to a high pressure turbine and the other controlling supply of reheated steam from said an intermediate or low pressure turbine, and a further pair of simul taneously operable valves for astern running or manoeuvring, 'one of said last mentioned valves controlling supply of superheated steam to said reheater and the other controlling supply of said steam from the reheater to an astern turbine.

5. An elastic fluid power installation as claimed inclaim 1 in combination with means for automatically controlling the means for reducing heating of the reheater in accordance with the temperature of the steam entering or leaving the reheater.

6. An' elastic fluid power installation as claimed in claim 1 in which the means for direct ing the steam to the astern turbine includes a valve yof the'double shut-off with leak-off type controlling the supply of reheated steam to the astern turbine. I

v STANLEY SMITH COOK.

ILOUIS MOR'IIMER DOUGLAS. 

